The present invention relates to a step bearing for axial support of an open-end spinning rotor in a spinning device of an open-end spinning machine. To support open-end spinning rotors, it is a known method to receive them in the nip of bearing disk pairs for radial support, whereby drive means or some other axial thrust having to be supported by an axial bearing is forced on them by the radial support. Open-end spinning rotors are provided with a shaft at the one end of which the rotor pot is mounted, within which fibers are fed pneumatically and are spun in to a yarn. At the end across from the rotor pot, the rotor shaft is supported axially in an axial bearing. Different embodiments of axial bearings for this are known in the state of the art.
EP 0435016 B1 shows an aerostatic axial bearing in which the rotor shaft bears upon a bearing plate subjected to compressed air. DE 19542908 A1 discloses an axial bearing for a rotor shaft in which the rotor shaft bears axially upon a ball that rotates together with the rotor shaft. Axial bearings in which the rotor shaft bears upon a ball that also rotates have been the preferred type of axial support of spinning rotors in the past. Such a support is shown, e.g., in DE 3533717 A1 as well as in DE 19652507 A1. The latter patent shows the replaceable ball located in a chamber filled with grease. In the axial support of the rotor shaft described in DE 19542908, a modified embodiment is shown in which the ball in turn bears upon additional balls and the balls are contained in a housing.
It is a disadvantage of the known axial bearings of spinning rotors that in part their assembly is awkward and time consuming, or that the axial bearing can become loose or can be difficult to adjust because it is installed directly on the machine frame, whereby the bearing is held perpendicularly to the direction of stress. A further disadvantage of axial bearings using a ball is that existing spinning devices can no longer operate economically because such axial bearings require a shaft end that extends clearly past the plane of the supporting disks, so that the rotor speed cannot be further increased because of the length of the rotor shaft, as otherwise inadmissible oscillations would occur. These oscillations can even result in a failure of the bearing.
It is therefore a principal object of the present invention to propose a new step bearing that is simple in construction, easy to assemble, easy to replace and that furthermore makes it possible to modernize open-end spinning devices in a simple manner, since they can now be operated with spinning rotors at speeds that may be considerably higher. Additional objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
This principal object is attained according to the invention through a step bearing for the axial support of an open-end spinning rotor in a spinning device of an open-end spinning machine, with a bearing body provided with a rest for the spinning rotor and a support on the machine side. The rest is made in the form of a flat bearing surface constituting the one end of the bearing body, while the other end of the bearing body is made as a supporting surface of the machine-side support. By using the step bearing of the present invention, the bearing can be made to be easily replaceable, since only the air arrival hose for the supply of compressed air to the bearing surface need be disassembled, while the rest of the support on the machine can remain essentially unchanged. According to the present invention, it is even possible to use an adjusting screw as in known axial ball bearings as a support on the machine with an axial bearing.
In addition, the bearing according to the invention has the added advantage that, with this bearing open-end spinning devices according to the state of the art can be refitted easily from an axial ball bearing to an aerostatic axial bearing. A refitting to another axial bearing can be achieved thereby. Beyond this, it is possible, to change the geometry of the axial bearing or the open-end spinning device thanks to the utilization of a step bearing according to the invention. Changing the geometry of the axial bearing or the open-end spinning device allows the shaft of the spinning rotor to be made considerably shorter and the supporting surface can be located directly at the end of the bearing body. As a result, it is possible to increase the rotor speeds significantly, since now rotor shafts can be used that are considerably shorter. At the same time it is even possible to use the previously used axial support on the machine, since the bearing according to the invention can also bear upon the known supports for the ball of an axial ball bearing.
In an especially advantageous further development of the invention, the flat bearing surface of the bearing according to the invention is made in the form of a bearing plate that can be subjected to compressed air, so that the step bearing advantageously becomes an aerostatic step bearing by means of which open-end spinning rotors can be securely supported with little need for maintenance. For this purpose, the bearing plate of the step bearing according to the invention is advantageously provided with bores for the passage of compressed air or with a bearing plate that is permeable, i.e., through which compressed air flows from the back into the bearing gap where it constitutes a compressed-air cushion on which the rotor shaft bears.
In an advantageous further development, the bearing body is provided with a connection for compressed air, whereby the connection is placed essentially at a right angle to the axis of the bearing body, and thus also at a right angle to the axis of the rotor shaft interacting with the step bearing. This makes it possible for the one end of the bearing body to be used in its entirety as a bearing surface for the support on the side of the machine, without space being required to integrate a compressed-air connection in this area. In addition, such a placement of the compressed-air connection has the advantage of being able to use existing components of machines to be retrofitted, in particular the axial support on the machine. Also, such a placement of the compressed-air connection creates room for the compressed-air connection of an aerostatic axial bearing, either because no or only few rebuilding measures are needed. In an especially advantageous further development of the invention, the bearing surface of the step bearing is designed for the support on the machine in such manner that it can be used with an already existing bearing device, e.g., for a ball. For this, the bearing surface advantageously can be provided with reinforcement on the bearing body. This reinforcement makes it possible to also use a bearing body made of plastic which can then interact with a support on the machine that has not been produced especially for a step bearing according to the invention. Most advantageously, this reinforcement makes it possible for the bearing body to be formed economically from a plastic while nevertheless possessing sufficient mechanical strength. In a further development of the invention the bearing plate is superimposed axially over the bearing body. This axial placement of the bearing plate over the bearing body is especially advantageous for the installation of the bearing plate on the bearing body, making it possible to design an especially short rotor shaft because, in that way, the bearing plate can be located especially close to the pair of supporting rollers across from it.
The bearing plate is most advantageously designed as a non-replaceable bearing plate on the bearing body, ensuring that the bearing plate can be integrated solidly in the bearing body. In addition, this advantageous configuration of the bearing plate allows the bearing plate to be combined most securely with the bearing body. This secure combination can be achieved advantageously, e.g., by bonding it into the base body or by pressing it into the base body. In an advantageous further development of the invention, the bearing body is at least in part cylindrical and on its circumference a bearing surface is formed to hold the bearing body in circumferential direction. This cylindrical design makes it possible to prevent a twisting of the bearing body through simple design of the seat in the spinning device.
In another advantageous further development of the invention, the bearing body is provided with a cylindrical form on its side towards the spinning rotor and with an angular cross-section on its side towards the support on the machine. Such a construction allows the bearing body to be held by simple means in its position in the open-end spinning machine, since an angular cross-section provides surfaces on which means to fix or to position it can be applied.
Additional advantageous further developments of the invention are found in the description of examples of embodiments. The invention is described below through drawings.